let sommeb2 a =
let n = vect_length a in
  fst ( iterer ( fun (mini, i)-> let (sf, minf, jf) = iterer ( fun (s, min,j)-> let t=s+a.(j) in if t<min then (t, t, j+1) else (t, min, j+1))
n-i-1
(0,mini,i)
in (minf, i+1))
n
(a.(0), 0));;